A comment leads me to repost Dane-Geld, a Kipling poem that I put up a few years ago. Today the Danes are the good guys rather than, as in the poem, the bad guys, and of course the fear isn't of nations but of extremist religious groups. But the principle is the same: When you give in to threats of violence, this just emboldens the threateners to demand more. What happens when someone wants to do a movie of Mohammed's life? Or says harsh things about Islam that some extremist Muslims find offensive or even blasphemous? Behavior that gets rewarded gets repeated.
In any case, here's the poem; it actually isn't one of Kipling's best from the standpoint of craft — his historical poems generally aren't, I think — but it's still pretty good:
It is always a temptation to an armed and agile nation
To call upon a neighbour and to say: --
"We invaded you last night — we are quite prepared to fight,
Unless you pay us cash to go away."
And that is called asking for Dane-geld,
And the people who ask it explain
That you've only to pay 'em the Dane-geld
And then you'll get rid of the Dane!
It is always a temptation for a rich and lazy nation,
To puff and look important and to say: --
"Though we know we should defeat you, we have not the time to meet you.
We will therefore pay you cash to go away."
And that is called paying the Dane-geld;
But we've proved it again and again,
That if once you have paid him the Dane-geld
You never get rid of the Dane.
It is wrong to put temptation in the path of any nation,
For fear they should succumb and go astray;
So when you are requested to pay up or be molested,
You will find it better policy to say: --
"We never pay any-one Dane-geld,
No matter how trifling the cost;
For the end of that game is oppression and shame,
And the nation that pays it is lost!"